Welcome to the latest edition of Ask John where renowned rugby historian John Griffiths will answer any rugby-related query you have!

So, if there's something you've always wanted to know about the game we love but didn't know who to ask, or you think you can stump our expert - then get involved by sending us a question.

In this edition, John Griffiths looks at the best All Blacks Test coaches of the professional era, Bill McLaren's Scotland trial, the first Welsh referee in French club matches, fickle half-back selection and 'the best player of all time.'

Graham Henry's winning percentage with the All Blacks is in the mid-80s and seems phenomenally good. How does that compare with other coaches who have had tenures lasting at least a couple of seasons since the game became professional?James Tipping, New Zealand

All four NZ Test head-coaches of the professional era have had 75% (or better) Test records:

Head Coach

Test Span

Played

Won

Drawn

Lost

Percentage

Graham Henry

2004 to 2011

103

88

0

15

85.43

John Mitchell

2002 to 2003

25

20

1

4

82.00

Wayne Smith

2000 to 2001

20

15

0

5

75.00

John Hart

1996 to 1999

41

31

1

9

76.83

Among others who had tenures lasting for at least two years, only Rod Macqueen for Australia can boast a Test record approaching Mitchell and Henry's. He steered the Wallabies through 43 Tests between November 1997 and July 2001 before standing down after the series with the Lions.

Australia won 34 and drew one of his Tests - an 80% success record. During his stewardship Australia won the World Cup, took a series off the Lions and never had to hand the Bledisloe Cup to New Zealand.

Sir Clive Woodward (like his predecessors Geoff Cooke and Jack Rowell before the start of the professional era) had 72% records as England's head coach/manager and Nick Mallett's record with South Africa (1997 to 2000) was 71%.

Can you provide any details of the late Bill McLaren's Final trial for Scotland?Andy Ross, New Zealand

The distinguished BBC commentator played from the Hawick club for the Rest against Scotland in the Final trial of the 1947-48 season. The trial was staged at Murrayfield on Saturday 20th December, 1947, and Bill played in the back-row for a side that upside the form-book by winning 8-0.

Scotland, however, were well-served by top-class back-row forwards at this time and the senior side's back-row of Elliot, Watt and Lees retained their places for the opening match of the Five Nations season against France a month later.

The fly-halves (Buchanan and Angus Cameron) and the centres (Gloag and Ogilvie) swapped sides after half-time. W A Todd of Bath came into the Rest back-row to replace Bill McLaren at the interval. The rugby correspondent of The Glasgow Herald, unsure as to why McLaren had been substituted, reported: "the Borderer's departure could not have arisen from his display."

Who was the first Welsh referee to control a French club match?Geoff James, Wales

It was common for Home Unions referees to take charge of French home Tests and friendly matches involving French clubs against visiting English-speaking teams as long ago as the years before the Great War.

The first Welshman to control a match between French clubs is thought to have been Trevor Jones of Maesteg. He took charge of the England-France international at Twickenham in 1947 - France's first Test at Twickenham for 17 years - and a few months later was invited to take control of the New Year's Day (1948) game between Nantes and Pau.

Was there ever a Five Nations tournament where one of the countries used different half-backs for every match? If not, what was the closest any team came? Graham Smith, England

The French used to be notorious for fickle selections but only once - in 1926 - did they call on seven different players (out of a maximum eight) to fill the fly-half and scrum-half roles in the old Five Nations. The only player who made two half-back appearances for them that season was Vincent Graule at fly-half. They used four different scrum-halves in their four games.

Even so, that only equalled the Championship record: Wales had also used seven for their Five Nations campaign in 1921.

Wales opened the season at Twickenham with Jack Wetter and Fred Reeves as their halves, recalled Tommy Vile (17 years since making his Test debut on the 1904 Lions tour and eight years since his last match for Wales) to partner new cap Willie Bowen against Scotland and retained Bowen to play with his Swansea club partner Tudor Williams against France. Finally, the Welsh selection committee turned to Clem Lewis and Archie Brown for the match in Belfast in March.

Who is the best player of all time and why?Joshua Peleti, Australia

How long is a piece of string?

It is impossible of course to compare across the generations - different physiques, different laws and the change from an amateur sport to one that is fully professional at Test level complicate the issue.

Statistically speaking there are several players (mostly one-cap merchants) who have 100% Test winning records - an objective criterion perhaps for answering this question. One player stands out, moreover, for playing on a winning side and scoring the winning points. His name is Denzil Thomas, the Neath and Llanelli fly-half-cum-centre who had a penchant for dropped goals. He played for Wales against Ireland at Lansdowne Road in 1954.

In his only Test appearance he scored Wales's winning points with a very late dropped goal. The scores were tied at 9-all with Wales attacking in the game's dying moments. Then, according to the veteran rugby writer Dai Gent of the Sunday Times, "Denzil Thomas kicked his goal, cleverly wriggling his way to get the opportunity."

It was Thomas's misfortune to be a Welsh centre at the same time as Bleddyn Williams, Malcolm Thomas, Gareth Griffiths, Glyn John and Alun Thomas. Had it not been for their presence, the man the Neath and Llanelli faithful nicknamed "Denzil Drop" would have won many more Welsh caps.

He was later a popular schoolmaster in South and West Wales. Max Wiltshire and Jim Shanklin were among the Welsh international players he nurtured while another former pupil, Brian Diment, emulated his master by dropping a goal for Swansea in their 9-8 victory over the 1966 Wallabies.